Deflecting end-plate construction for vacuum-type circuit interrupters

ABSTRACT

A vacuum-type circuit interrupter has a generally hollow deflecting end-plate construction involving in one embodiment a pair of spaced metallic diaphragms, so as to be axially resilient during the closing operation of the circuit interrupter, and thereby to absorb the impact stresses during such a closing operation. In one construction, a resilient diaphragm has its peripheral edge sealed to the end wall of the insulating casing, and said diaphragm is reinforced by an annular ring-shaped cup member secured to the first-mentioned diaphragm, and also to the stationary stem portion of the stationary contact or electrode of the vacuum-type circuit interrupter. A second construction involves the use of a pair of spaced ringshaped, or annular diaphragm members, which are secured, as by a brazing operation, to the stationary stem portion of the electrode constituting the stationary contact. A pair of inner concentric spacing sleeves may be employed, and an outer sleevelike member may be secured, as by brazing, to the assembly of the two annular members and also to their outer spacing sleeve. This outer sleeve-like member may also be secured, in sealing engagement, with one end of the insulating casing for the vacuumtype circuit interrupter. Another embodiment may include a reinforcing diaphragm merely in abutment with the stationary stem. An elastomeric material, such as rubber, may fill the hollow space of the end plate to serve as a damping function.

United States Patent Cherry et al.

[54] DEF LECTING END-PLATE CONSTRUCTION FOR VACUUM-TYPE CIRCUIT INTERRUPTERS [72] Inventors: Sidney J. Cherry, Elmira; Paul 0. Wayland, Montour Falls; Albert Bereza, El-

mira, all of NY.

[73] Assignee: Westinghouse Electric Corporation, Pittsburgh, Pa.

[22] Filed: Mar. 27, 1969 [21] Appl. No.: 811,006

[52] US. Cl ..200/144 B [5 1] Int. Cl. ..HOlh 33/66 [5 8] Field of Search ..200/144.2

[56] References Cited UNITED STATES PATENTS 2,740,867 4/1956 Jennings ..200/l44.2 2,979,588 4/1961 Jennings ZOO/144.2

2,993,970 7/1961 Yanagisawa.... 200/144.2

3,440,376 4/l969 Rabinowitz ..200/1442 3,129,308 4/1964 Yokoyama ..200/144 B FOREIGN PATENTS 0R APPLICATIONS 563,140 11/1932 Germany ..200/1442 724,810 9/l942 Germany ..200/l44.2

Primary E.\(|Illi)lfR0b6li S. Macon Attorney-A. T. Stratton, C. L. McHale and W. R. Crout 1151 3,657,502 Apr. 18, 1972 [57] ABSTRACT A vacuum-type circuit interrupter has a generally hollow deflecting end-plate construction involving in one embodiment a pair of spaced metallic diaphragms, so as to be axially resilient during the closing operation of the circuit interrupter, and thereby to absorb the impact stresses during such a closing operation. In one construction, a resilient diaphragm has its peripheral edge sealed to the end wall of the insulating casing, and said diaphragm is reinforced by an annular ringshaped cup member secured to the first-mentioned diaphragm,-and also to the stationary stem portion of the stationary contact or electrode of the vacuum-type circuit interrupter.

A second construction involves the use of a pair of spaced ring-shaped, or annular diaphragm members, which are secured, as by a brazing operation, to the stationary stem portion of the electrode constituting the stationary contact. A pair of inner concentric spacing sleeves may be employed, and an outer sleeve-like member may be secured, as by brazing, to the assembly of the two annular members and also to their outer spacing sleeve. This outer sleeve-like member may also be secured, in sealing engagement, with one end of the insulating casing for the vacuum-type circuit interrupter.

Another embodiment may include a reinforcing diaphragm merely in abutment with the stationary stem. An elastomeric material, such as rubber, may fill the hollow space of the end plate to serve as a damping function.

6 Claims, 3 Drawing Figures PATENTEDAPR 18 I972 FIGI 3 ELASTOMETRIC MATERIAL' FIG. 2

ill

b lo 230 RRN INVENTORS S|dney J. Cherry, Poul O.Woylond WITNESSES WZM DEF LECTING END-PLATE CONSTRUCTION FOR VACUUM-TYPE CIRCUIT INTERRUIIERS BACKGROUND OF THE INVENTION Vacuum-type circuit interrupters are somewhat unique when compared with other electronic tubes employing metalto-insulator seals, in that, as part of their operation, they must withstand high impactive shocks and still remain vacuumtight. It is a distinct problem in the art to obtain an end-plate construction for a vacuum-type circuit interrupter, which will retain its sealing qualities and, in addition, will be able to withstand the high impact shocks during a closing operation of the vacuum interrupter. These may, for certain applications, number in the millions of operations, such as for motor-starting duty.

Generally, the prior art constructions have utilized a heavy metal end plate, which serves to close one end of the vacuumtype circuit interrupter. Reference may be made to US. patent application filed Mar. 19, 1968, Ser. No. 714,197 by Joseph Lempert and Gerald R. Kotler entitled Gettering Arrangements for Vacuum-type Circuit Interrupters, for a description of a typical prior-art type of vacuum circuit interrupter utilizing a heavy end-plate construction.

SUMMARY OF THE INVENTION According to a preferred embodiment of the invention, the end-plate construction for a vacuum-type circuit interrupter, supporting the stationary contact thereof, is of generally hol low construction and is constructed of a pair of spaced generally flexible metallic diaphragm members, which will enable the vacuum interrupter to withstand high closing impact shocks, of a considerable number, and yet retain its sealing characteristics, which are essential.

According to another preferred embodiment of the invention, a pair of ring-shaped plates, or diaphragms are spaced apart by a pair of concentric spacing sleeves, and have their outer peripheries secured, as by brazing, to an annular outer member, which, in turn, is sealed to the end of the insulating casing.

It is a general object of the present invention to provide an improved vacuum-type circuit interrupter which will maintain its evacuated condition, and yet will be able to withstand high shock forces during the many closing operations of the interrupter.

Another object of the present invention is to provide an improved end-plate construction for a vacuum-type circuit interrupter which is of a generally hollow construction.

Still a further object of the present invention is to provide an improved generally hollow-end-plate construction for a vacuum-type circuit interrupter, which will provide a deflecting end-plate construction and yet will utilize a minimum of mass to avoid losses due to hysteresis and eddy currents.

Further objects and advantages will readily become apparent upon reading the following specification, taken in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a vertical sectional view taken through a vacuumtype circuit interrupter embodying the principles of the present invention, the contact structure being illustrated in the closed-circuit position;

FIG. 2 is a fragmentary view showing an alternate type of end-plate construction, which may be utilized in place of that illustrated in FIG. 1; and,

FIG. 3 is a fragmentary view showing a further modified construction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawing and more particularly to FIG. 1 thereof, it will be noticed that there is shown a highly-evacuated envelope 1 comprising a casing 2 of suitable insulating material, such as ceramic or glass, and a pair of metallic end plate constructions 3 and 4 closing off the ends of the casing. Suitable seals 5 are provided between the end-plate constructions 3, 4 and the casing 2 to render the envelope 1 vacuumtight. The normal pressure within the envelope 1, under static conditions, is lower than 10' torr. so that a reasonable assurance is had that the mean free path for electrons will be longer than the potential breakdown paths within the envelope 1.

Located within the envelope 1 is a pair of relatively movable disc-shaped contacts, or electrodes 7 and 8, shown in full lines in their separated, or opemcircuit position. When the contacts 7, 8 are separated, there is an arcing gap 9 located therebetween. The upper contact 7 is a stationary contact suitably secured to a conductive rod 10, which at its upper end is united to the upper end plate construction 3. The lower contact 8 is a movable contact joined to a conductive operating rod 11, which is suitably mounted for reciprocal movement. The operating rod 11 projects through an opening 12 in the lower end plate construction 4, and a flexible metallic bellows 14 provides a seal about the rod 11 to allow for reciprocal opening and closing movement of the rod 11 without impairing the vacuum inside the envelope 1. As shown in FIG. 1, the bellows 14 is secured in sealing relationship at its respective opposite ends 14a, 14b to the operating rod 11 and to the end cap 4.

Coupled to the lower end of the operating rod 1], suitable actuating means (not shown) is provided for driving the movable contact 8 upwardly into abutting engagement with the stationary contact 7 so as to close the interrupter device. The closed position of the movable contact 8 is indicated by the dotted lines 15. The actuating means is also capable of returning the contact 8 to its illustrated solid-line open position, so as to open the interrupter. A circuitopening operation will, for example, entail a typical gap length, or separation distance, when the contacts 7, 8 are fully opened, of perhaps one-half inch.

The are 17 which is established across the gap 9 between the electrodes 7, 8, as the electrodes are opened, and also when they are closed, vaporizes some of the contact material, and these vapors are dispersed from the arcing gap 9 toward the envelope casing 2. In the illustrated interrupter, the internal insulating surfaces 2a of the casing 2 are protected from the condensation of arc-generated metallic vapor and particles thereon by means of a tubular metallic shield 18 suitably supported, as at 18a, to the casing 2 and preferably isolated from both end caps 3, 4. This shield 18 acts to intercept and to condense arc-generated metallic vapors before they can reach the internal wall surfaces of the casing 2. To reduce the chances for vapor bypassing the shield 18, a pair of end shields 19, 20 are provided at opposite ends of the central shield 18.

We have discovered that the vacuum-type circuit interrupter is somewhat unique when compared with other electronic tubes employing metal-to-insulator seals in that, as a part of its operation, it must withstand high impactive shock and still remain vacuum-tight. Recent tests, as well as analytical study, have shown the desirability of treating the end of the interrupter as a spring in which the deflection constant spring rate and amount of pennissible deflection are controlled and optimized for maximum ability to store the impactive energy. One way to achieve spring rate variations of the end is to use a single plate diaphragm end; however, this has produced difficulty in retaining adequate rocking stiffness, and in most designs reinforcement of the end with solid stiffeners leads to a configuration in which the allowable deflection is not optlmum.

Our invention is concerned with a structure which allows the spring rate of the end plate 3 to be optimized without loss of rocking stiffness, and with ability of the end 3 to take maximum deflection. The type of structure which makes this possible is shown in FIG. 1 and is composed basically of a diaphragm end 3, which is of generally hollow construction.

The generally hollow end plate construction 3 comprises an inner diaphragm member 22 of metal, such as stainless steel,

having its outer periphery sealed, as at 5, to the upper end of the casing 2. The stainless steel diaphragm has a central hole 22a provided therethrough, which abuts the shoulder portion a of the stationary electrode stem 10. An annular generally cup-shaped diaphragm member 23 made of metal, such as stainless steel, Kovar Scott U.S. Pat. Nos. 1,942,260,

, 1,942,261 2,057,452 2,279,168), or a nickel-iron alloy,

for example, is secured as by brazing at 230, to the upper surface of the inner diaphragm member 22 and also has a neck portion 23b secured, as by brazing, to the shank portion 10b of the electrode stem 10.

The outer cup-shaped diaphragm member 23 is relatively stiff in a radial direction, but is springy in the axial direction denoted by the arrow Y. This will dissipate impact energy without putting excessive stress on headers which may lead to distortion or fatigue failure after a number of closing operations.

The hollow end-plate construction, or header 3 has less mass and therefore is easier to outgas than a heavier section.

FIG. 2 is another possible embodiment of the idea, of which many can be envisioned. In FIG. 2, an axially-spaced pair of diaphragm members 25, 26 are provided. They are made of a suitable metallic material, such as stainless steel, for example, and are spaced axially apart by a pair of radially-spaced concentrically-arranged pair of spacing sleeves 28, 29. The latter are secured, as by brazing, to both diaphragm members 25, 26 to the electrode stem shank portion 10b, and to an outer metallic support sleeve 31. The metallic sleeve 31 is not only secured, as by brazing, to the diaphragm members 25, 26 and outer sleeve 29, but also makes the seal 5 with the upper end of casing 2.

FIG. 3 shows a further modification in which the outer diaphragm member 23 is similar to the construction shown in FIG. 1, but instead of brazing the inner periphery 23'a to the electrode shank portion 1012, instead an abutment therebetween is provided. Within the space S provided within the generally hollow-end-plate construction 3" an elastomeric material, such as rubber, polyurethane, or a similar elastomeric material may be filled within the hollow section to dampen the shock and to minimize bouncing.

Another advantage of the idea, when coupled with vacuuminterrupter usage, is that the losses due to hysteresis and eddycurrent induction are a minimum due to the employment of low mass ends and thin sections.

From the foregoing discussion, it will be apparent that there has been .provided an improved deflecting end-plate construction, of generally hollow configuration, for a vacuum type circuit-interrupter, in which a minimum of mass is utilized, and yet the sealing characteristics are retained by the capability of the hollow end-plate construction absorbing impact shocks during the many closing operations of the circuit interrupter.

Although there has been illustrated and described specific structures, it is to be clearly understood that the same were merely for the purpose of illustration, and that changes and modifications may be readily made therein by those skilled in the art, without departing from the spirit and scope of the invention.

We claim as our invention:

1. A vacuum-type circuit interrupter comprising, in combination:

a. means defining an outer evacuated cylindrical casing at least partially of insulating material;

b. a pair of separable contacts disposed within said casing;

c. one of said separable contacts being a stationary contact having a stationary supporting stem;

d. a flexible hollow end-plate construction for said evacuated cylindrical casing for supporting said stationary supporting steam and fixedly secured thereto;

e. said flexible end-plate construction comprising a pair of axially-spaced flexible diaphragm members;

f. at least one of said flexible diaphragm members being affixed to said stationarysup ortin stem. 2. A vacuum-type circuit in errup er comprising, in combination, means defining an outer evacuated cylindrical casing at least partially of insulating material, a pair of separable contact disposed within said casing, one of said separable contacts being a stationary contact having a stationary supporting stem, a flexible end-plate construction for said evacuated cylindrical casing for supporting said stationary supporting stem, said flexible end-plate construction comprising a pair of axiallyspaced flexible diaphragm members, at least one of said flexible diaphragm members being affixed to said stationary supporting stem, and the space between the spaced diaphragm members being at least partially filled with an elastomeric material to dampen the motion of the diaphragm members.

3. The combination of claim 1, wherein both spaced diaphragm members are fixedly attached to the electrode stem supporting the stationary contact of the interrupter.

4. The combination of claim 1, wherein the outer of the two spaced diaphragm members merely abuts the electrode stem supporting the stationary contact of the interrupter.

5. A vacuum-type circuit interrupter comprising, in combination, means defining an outer evacuated cylindrical casing at least partially of insulating material, a pair of separable contacts disposed within said casing, one of said separable contacts being a stationary contact having a stationary supporting stem, a flexible end-plate construction for said evacuating cylindrical casing for supporting said stationary supporting stem, said flexible end-plate construction comprising a pair of axially-spaced flexible diaphragm members, at least one of said flexible diaphragm members being affixed to said stationary supporting stem, a pair of radially-spaced concentrically-arranged spacing sleeves being provided, the inner one of which is attached to both the inner extremities of the diaphragm members and also to the electrode stem supporting the stationary contact of the interrupter.

6. The combination of claim 1 wherein the outer of the spaced diaphragm members is of annular cup-shaped configuration. 

1. A vacuum-type circuit interrupter comprising, in combination: a. means defining an outer evacuated cylindrical casing at least partially of insulating material; b. a pair of separable contacts disposed within said casing; c. one of said separable contacts being a stationary contact having a stationary supporting stem; d. a flexible hollow end-plate construction for said evacuated cylindrical casing for supporting said stationary supporting stem and fixedly secured thereto; e. said flexible end-plate construction comprising a pair of axially-spaced flexible diaphragm members; f. at least one of said flexible diaphragm members being affixed to said stationary supporting stem.
 2. A vacuum-type circuit interrupter comprising, in combination, means defining an outer evacuated cylindrical casing at least partially of insulating material, a pair of separable contacts disposed within said casing, one of said separable contacts being a stationary contact having a stationary supporting stem, a flexible end-plate construction for said evacuated cylindrical casing for supporting said stationary supporting stem, said flexible end-plate construction comprising a pair of axially-spaced flexible diaphragm members, at least one of said flexible diaphragm members being affixed to said stationary supporting stem, and the space between the spaced diaphragm members being at least partially filled with an elastomeric material to dampen the motion of the diaphragm members.
 3. The combination of claim 1, wherein both spaced diaphragm members are fixedly attached to the electrode stem supporting the stationary contact of the interrupter.
 4. The combination of claim 1, wherein the outer of the two spaced diaphragm members merely abuts the electrode stem supporting the stationary contact of the interrupter.
 5. A vacuum-type circuit interrupter comprising, in combination, means defining an outer evacuated cylindrical casing at least partially of insulating material, a pair of separable contacts disposed within said casing, one of said separable contacts being a stationary contact having a stationary supporting stem, a flexible end-plate construction for said evacuating cylindrical casing for supporting said stationary supporting stem, said flexible end-plate construction comprising a pair of axially-spaced flexible diaphragm members, at least one of said flexible diaphragm members being affixed to said stationary supporting stem, a pair of radially-spaced concentrically-arranged spacing sleeves being provided, the inner one of which is attached to both the inner extremities of the diaphragm members and also to the electrode stem supporting the stationary contact of the interrupter.
 6. The combination of claim 1 wherein the outer of the spaced diaphragm members is of annular cup-shaped configuration. 